package com.project.m.api.busi.util;

public final class Base64 {

    /** */
    private static final int BASELENGTH = 255;

    /** */
    private static final int LOOKUPLENGTH = 64;

    /** */
    private static final int TWENTYFOURBITGROUP = 24;

    /** */
    private static final int EIGHTBIT = 8;

    /** */
    private static final int SIXTEENBIT = 16;

    /** */
    private static final int FOURBYTE = 4;

    /**
     * The sign bit as an int
     */
    private static final int SIGN = -128;

    /**
     * The padding character
     */
    private static final byte PAD = (byte) '=';

    /**
     * The alphabet
     */
    private static final byte[] BASE64_ALPHABET = new byte[BASELENGTH];

    /**
     * The lookup alphabet
     */
    private static final byte[] LOOKUP_BASE64_ALPHABET = new byte[LOOKUPLENGTH];

    static {

        for (int i = 0; i < BASELENGTH; i++) {
            BASE64_ALPHABET[i] = -1;
        }
        for (int i = 'Z'; i >= 'A'; i--) {
            BASE64_ALPHABET[i] = (byte) (i - 'A');
        }
        for (int i = 'z'; i >= 'a'; i--) {
            BASE64_ALPHABET[i] = (byte) (i - 'a' + 26);
        }

        for (int i = '9'; i >= '0'; i--) {
            BASE64_ALPHABET[i] = (byte) (i - '0' + 52);
        }

        BASE64_ALPHABET['+'] = 62;
        BASE64_ALPHABET['/'] = 63;

        for (int i = 0; i <= 25; i++) {
            LOOKUP_BASE64_ALPHABET[i] = (byte) ('A' + i);
        }

        for (int i = 26, j = 0; i <= 51; i++, j++) {
            LOOKUP_BASE64_ALPHABET[i] = (byte) ('a' + j);
        }

        for (int i = 52, j = 0; i <= 61; i++, j++) {
            LOOKUP_BASE64_ALPHABET[i] = (byte) ('0' + j);
        }
        LOOKUP_BASE64_ALPHABET[62] = (byte) '+';
        LOOKUP_BASE64_ALPHABET[63] = (byte) '/';

    }

    /**
     * Return true if the specified octect is base64
     *
     * @param octect The octet to test.
     * @return boolean True if the octect is base64.
     */
    static boolean isBase64(byte octect) {
        // Should we ignore white space?
        return (octect == PAD || BASE64_ALPHABET[octect] != -1);
    }

    /**
     * 编码
     *
     * @param source  源字符串
     * @param charset 字符编码
     * @return 编码结果
     */
    public static String encode(String source, String charset) {
        try {
            byte[] ret = encode(source.getBytes(charset));
            String str = new String(ret, charset);
            return str;
        } catch (Exception ex) {
            return "";
        }
    }

    /**
     * Encodes hex octects into Base64
     *
     * @param binaryData Array containing binaryData
     * @return Base64-encoded array
     */
    public static byte[] encode(byte[] binaryData) {

        int lengthDataBits = binaryData.length * EIGHTBIT;
        int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
        int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
        byte encodedData[] = null;

        if (fewerThan24bits != 0) { // data not divisible by 24 bit
            encodedData = new byte[(numberTriplets + 1) * 4];
        } else { // 16 or 8 bit
            encodedData = new byte[numberTriplets * 4];
        }

        byte k = 0;
        byte l = 0;
        byte b1 = 0;
        byte b2 = 0;
        byte b3 = 0;
        int encodedIndex = 0;
        int dataIndex = 0;
        int i = 0;
        for (i = 0; i < numberTriplets; i++) {

            dataIndex = i * 3;
            b1 = binaryData[dataIndex];
            b2 = binaryData[dataIndex + 1];
            b3 = binaryData[dataIndex + 2];

            l = (byte) (b2 & 0x0f);
            k = (byte) (b1 & 0x03);

            encodedIndex = i * 4;
            byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2)
                    : (byte) ((b1) >> 2 ^ 0xc0);

            byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4)
                    : (byte) ((b2) >> 4 ^ 0xf0);
            byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6)
                    : (byte) ((b3) >> 6 ^ 0xfc);

            encodedData[encodedIndex] = LOOKUP_BASE64_ALPHABET[val1];
            encodedData[encodedIndex + 1] = LOOKUP_BASE64_ALPHABET[val2
                    | (k << 4)];
            encodedData[encodedIndex + 2] = LOOKUP_BASE64_ALPHABET[(l << 2)
                    | val3];
            encodedData[encodedIndex + 3] = LOOKUP_BASE64_ALPHABET[b3 & 0x3f];
        }

        // form integral number of 6-bit groups
        dataIndex = i * 3;
        encodedIndex = i * 4;
        if (fewerThan24bits == EIGHTBIT) {
            b1 = binaryData[dataIndex];
            k = (byte) (b1 & 0x03);
            byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2)
                    : (byte) ((b1) >> 2 ^ 0xc0);
            encodedData[encodedIndex] = LOOKUP_BASE64_ALPHABET[val1];
            encodedData[encodedIndex + 1] = LOOKUP_BASE64_ALPHABET[k << 4];
            encodedData[encodedIndex + 2] = PAD;
            encodedData[encodedIndex + 3] = PAD;
        } else if (fewerThan24bits == SIXTEENBIT) {
            b1 = binaryData[dataIndex];
            b2 = binaryData[dataIndex + 1];
            l = (byte) (b2 & 0x0f);
            k = (byte) (b1 & 0x03);

            byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2)
                    : (byte) ((b1) >> 2 ^ 0xc0);
            byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4)
                    : (byte) ((b2) >> 4 ^ 0xf0);

            encodedData[encodedIndex] = LOOKUP_BASE64_ALPHABET[val1];
            encodedData[encodedIndex + 1] = LOOKUP_BASE64_ALPHABET[val2
                    | (k << 4)];
            encodedData[encodedIndex + 2] = LOOKUP_BASE64_ALPHABET[l << 2];
            encodedData[encodedIndex + 3] = PAD;
        }
        return encodedData;
    }

    /**
     * 解码
     *
     * @param source  源字符串
     * @param charset 字符编码
     * @return 解码结果
     */
    public static String decode(String source, String charset) {
        try {
            byte[] ret = decode(source.getBytes(charset));
            String str = new String(ret, charset);
            return str;
        } catch (Exception ex) {
            return "";
        }
    }

    /**
     * Decodes Base64 data into octects
     *
     * @param base64Data byte array containing Base64 data
     * @return Array containing decoded data.
     */
    public static byte[] decode(byte[] base64Data) {
        // Should we throw away anything not in base64Data ?

        // handle the edge case, so we don't have to worry about it later
        if (base64Data.length == 0) {
            return new byte[0];
        }

        int numberQuadruple = base64Data.length / FOURBYTE;
        byte decodedData[] = null;
        byte b1 = 0, b2 = 0, b3 = 0, b4 = 0, marker0 = 0, marker1 = 0;

        int encodedIndex = 0;
        int dataIndex = 0;
        {
            // this block sizes the output array properly - rlw
            int lastData = base64Data.length;
            // ignore the '=' padding
            while (base64Data[lastData - 1] == PAD) {
                if (--lastData == 0) {
                    return new byte[0];
                }
            }
            decodedData = new byte[lastData - numberQuadruple];
        }

        for (int i = 0; i < numberQuadruple; i++) {
            dataIndex = i * 4;
            marker0 = base64Data[dataIndex + 2];
            marker1 = base64Data[dataIndex + 3];

            b1 = BASE64_ALPHABET[base64Data[dataIndex]];
            b2 = BASE64_ALPHABET[base64Data[dataIndex + 1]];

            if (marker0 != PAD && marker1 != PAD) { // No PAD e.g 3cQl
                b3 = BASE64_ALPHABET[marker0];
                b4 = BASE64_ALPHABET[marker1];

                decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
                decodedData[encodedIndex + 1] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
                decodedData[encodedIndex + 2] = (byte) (b3 << 6 | b4);
            } else if (marker0 == PAD) { // Two PAD e.g. 3c[Pad][Pad]
                decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
            } else if (marker1 == PAD) { // One PAD e.g. 3cQ[Pad]
                b3 = BASE64_ALPHABET[marker0];
                decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
                decodedData[encodedIndex + 1] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
            }
            encodedIndex += 3;
        }
        return decodedData;
    }
}